Hitherto, as dyes for dyeing mixed fibers of polyester fibers and cellulose fibers to provide Turkish blue-dyed mixed fibers, the dyes shown by the following formula are known as described in Japanese Patent Application (OPI) No. 24,489/78. (The term (OPI) as used herein refers to "published unexamined Japanese patent application".) ##STR2## wherein, [Cu-Pc] represents a copper phthalocyanine residue; m represents a number of about 0.2 and n represents a number of about 2.5.
However, these dyes are not always sufficient in color fastness to washing and color fastness to dry cleaning and hence the improvement of these dyes have been desired.